When most people think of the green economy, they conjure images of cutting-edge research and technology. In reality, some environmentally focused jobs were around long before the term "green collar" was invented, and certified vehicle emission inspector is one of them. After all, cars and trucks are the single biggest source of air pollution in the U.S., and emission inspectors are working constantly to keep that pollution in check [source: Union of Concerned Scientists].

Emission inspectors typically work at dedicated inspection facilities where they use a variety of equipment to make sure that cars and trucks conform to emissions standards set by the U.S. Environmental Protection Agency [source: EPA]. The job can be physically demanding from time to time since emission inspectors will occasionally need to lift heavy equipment, and inspectors should also be able to tolerate hot and cold weather since they'll be outside a lot. Finally, applicants will also need to undergo their state's certification process, which might require classroom training, as well as written examinations. For retirees with a background in auto repair and a passion for helping the environment, however, working as an emission inspector can be a rewarding job.